In systems based on a 3GPP LTE (Long Term Evolution) standard, user equipments (UEs) negotiate with the infrastructure (e.g., with evolved NodeBs, or eNBs) in order to transmit uplink data. To initiate such a negotiation, a UE transmits a Scheduling Request (SR) to an eNB. The UE may transmit an SR when the UE actually has uplink data to transmit, or the UE may transmit an SR periodically, regardless of whether or not the UE has data to transmit. After receiving an SR, the eNB may grant the SR by transmitting an SR grant to the UE. The SR grant indicates to the UE that the eNB is providing resources for the UE to transmit additional information, including information indicating the amount of uplink data that the UE has to transmit. Upon receiving an SR grant, the UE transmits the eNB an indication of the amount of uplink data in the form of a Buffer Status Report (BSR). Assuming sufficient system resources (e.g., resource blocks or RBs) are available for the UE to transmit that amount of uplink data, the eNB may transmit an uplink assignment to the UE. The uplink assignment indicates the system resources that the eNB has assigned to the UE (e.g., transmission parameters and an indicator of the quantity of data that the UE may transmit). Upon receiving the uplink assignment, the UE may initiate transmission of the data using the assigned resources.
At times, multiple UEs in a cell or sector may transmit SRs to an eNB during a same subframe. When sufficient downlink resources (e.g., resource blocks) are available for the eNB to transmit SR grants to all of the requesting UEs, the eNB may grant each of the multiple SRs (e.g., the eNB may transmit SR grants to each of the UEs). However, when sufficient downlink resources are not available for the eNB to transmit SR grants to all of the requesting UEs, conventional eNBs may either ignore or discard some of the SRs.
In some cases, a UE may have particularly time sensitive and important uplink data that the UE needs to transmit. Unfortunately, however, conventional eNBs generally lack the ability to consider the importance of uplink data when deciding which SRs the eNB will grant or ignore. Accordingly, conventional systems may impose undesirably large latencies on time sensitive and important uplink data that a UE desires to transmit to the system. Thus, what are needed are methods and apparatus for wireless communication systems to grant SRs in a more intelligent manner.